1. Field of the Invention
The present invention generally relates to footwear construction and in particular to the use of shock absorption and stabilizing members incorporated into the heel portion of the midsole of the footwear defined by a fluid-filled bladder in combination with a lower concave, shock absorbing cantilever support surface.
2. Prior Art
The result of the increased popularity of exercise, as well as the necessities of everyday walking and standing, it has been recognized there is a need to alleviate and relieve the stress imposed on a person""s feet and legs. In particular, it is essential that shoes and other like footwear provide for suitable shock absorption and stability. This is particularly important where the shoes or footwear are to be used in active pursuits such as running or other athletic endeavors.
As a general rule, it is the midsole of a shoe that provides the cushioning and stability to the foot of a user. In conventional shoes used for athletic purposes, either polyurethane foam, EVA (ethyl vinyl acetate) foam or perhaps HYTREL foam is used as the material which provides most of the cushioning of the shoe (HYTREL is a trademark of DuPont de Numerus and Co.). As stated, advanced shock absorption and stability is particularly required in athletic footwear where the user""s foot is exposed to repeated shocks from footstep impact in running and other athletic activities.
The prior art discloses a variety of footwear designs which have been developed for the purpose of improving shock absorption and stability. These prior art designs range from merely constructing the shoe sole from a softer, more resilient material to incorporating fluid-filled pads or bladders in the midsole of a shoe. In many shoe midsoles designed to increase the cushioning effects of the shoe, the increased resiliency or softness of the shoe sole provides no resistance to the tendency of the user""s foot to rotate relative to the leg upon impact, a condition generally referred to as pronation. The tendency for excessive lowering of the medial margin of the foot or excessive pronation, and a tendency for an excessive raising of the medial margin of the foot, or supination, have the potential of causing injuries to the wearer of the shoe.
One of the footwear designs disclosed by the prior art comprises a pair of tabs extending from opposite sides of the outsole of the shoe to the heel counter of the shoe for the purpose of connecting the outsole to the heel counter and increasing the lateral medial stability of the shoe. In this design, the tabs are formed as an integral part of the shoe outsole and are bonded to a heel wedge layer and midsole layer of the shoe sole as well as the heel counter. The inadequacy of this design is inherent in its construction. Since the tabs are secured to the extreme outer edges of the heel wedge and midsole, this will reduce the ability of the tabs to resist compression of the heeled wedge and midsole in the areas of the wedge and midsole inside the shoe surrounding the user""s foot.
Another design for footwear disclosed by the prior art employs one or more shock absorbers embedded within the heel portion of the midsole. The shock absorbers are typically air or fluid filled cylinders which can absorb the force of the heel and then return the energy in a controlled upward direction. Irrespective of the number of fluid filled cylinders embedded within the heel, excessive pronation of the user""s foot will occur since the air cylinders cannot properly respond to the difference in forces imposed on the medial and lateral portions of the heel.
The present invention resolves the inadequacies of the devices taught by the prior art. A footbed support platform is disposed beneath the heel and arch of the midsole. A fluid-filled bladder is disposed adjacent the bottom surface of the upper footbed support in the heel portion of the midsole. The bladder defines an interior, sealed cavity and comprises a peripheral channel which is positioned adjacent the periphery of the bladder and a plurality of transversely oriented channels which intersect with the peripheral channel of the sealed bladder. The bladder cavity is pressurized to atmospheric pressure. The upper surface of the bladder is adapted to snugly engage the bottom surface of the footbed support platform. The lower surface of the heel assembly defines a concave cantilever surface substantially bisected by the longitudinal axis of the heel section of the footwear. The combination of the footbed support platform, the fluid-filled bladder and the lower concave, cantilever surface provides improved shock absorption and stability to footwear.
The present invention relates to a multilayered structural assembly for the sole of footwear which improves shock absorption and stability. The midsole of the footwear has heel, midfoot and forefoot regions and an upper and lower surface. A footbed support platform is disposed adjacent the bottom surface of the midsole to the midfoot region which is commonly known as the arch. The lower surface of the footbed support platform is adapted to receive and be placed adjacent fluid-filled bladders which includes an internal, sealed cavity which is pressurized to ambient pressure. The fluid, preferably air, is disposed within the sealed cavity which is defined by a peripheral channel and a plurality of parallel, intersecting channels which are disposed substantially perpendicular to the longitudinal axis of the heel regions of the footwear. The intersecting channels are in communication with one another and the peripheral channel of the sealed cavity. The lower element of the heel assembly defines a concave, cantilever surface which is depressed when force is imposed upon the heel of the midsole. The combination of the footbed support platform, the fluid-filled bladder and the lower support element incorporating a cantilever surface provides improved shock absorption and stability.
It is an object of the present invention to provide construction for footwear which improves shock absorption and stability.
It is another object of the present invention to provide improved shock absorption and stability for shoes through the use of cooperating shock absorbing elements.
It is still another objection of the present invention to provide improved shock absorption for shoes through the use of a pressurized, fluid-filled bladder disposed within the heel region of the footwear.
It is still yet another object of the present invention to provide improved, dynamic stability for a shoe through the use of a cooperating fluid-filled bladder and a deflectable support platform in the heel region of the footwear.
It is still yet another object of the present invention to provide footwear incorporating an improved shock absorption and stability system which is simple and inexpensive to fabricate.
The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objectives and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawing in which a presently preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only, and is not intended as a definition of the limits of the invention.